Can I tow a Z3 manual transmission with a tow dolly?

[palmilla]

I am towing a Nissan pickup 4 down with my motorhome and my wife asked me to tow her 2000, Z3 manual transmission BMW instead.

I've checked out several RV sites and the talked about the automatic transmission and the problems you can have. Since I don't have an automatic transmission their views did not affect me. So, that is why I'm coming to you.


What are your thoughts about towing a manual transmission Bimmer? I am thinking of a tow dolly with two wheels up.


I would love to gleam from all your knowledge and advise me of any problems I might incur and anything that I might need to know before I purchase a tow dolly.

Thanks

[Nijapo]

As long as it's in neutral the transmission is disengaged. I wouldn't see any issues with it but then again I've never towed or RVed before so I don't have that niche knowledge.

[dmurray14]

IIRC you do NOT want to do this as the trans cooler operates off of the engine side of the transmission. Having the rear wheels spin will heat up the trans but will not cool it because nothing is spinning on the engine side.

You will probably want to double check with someone who is more knowledgable about this than myself, but that is what I seem to remember.

Dan

[palmilla]

I will look into the cooling problem.

Thanks for your insite.... but maybe I can get others to comment too.

John

[JoshS]

You need a driveshaft disconnect to tow with the rear wheels on the ground.

If you are dead-set on using a dolly instead of a trailer and don't want to modify the car, put the back wheels on the dolly and rig some proper taillights on the front end of the Z3. Most people who do this rely on the steering column lock, but I've read a better approach is to unlock that but rig another way to lock (or mostly lock, think bungee cords) the steering.

Personally, I opted for a trailer when I went through this. A good tilt-bed is quick and easy to load, unlike something with ramps. Don't get a rollback, that's a pain for long RVs.

[djb2]

You only need to disconnect the driveshaft if you are towing more than a limited number of miles -- 30 or 50 miles. Check your owners manual to find the recommended limit.

The problem isn't a pump -- the manual transmission doesn't have a pump. The problem is that with the car in neutral and the engine off, none of the gears inside the transmission spin. Only the output shaft spins. Without the gear teeth dipping into the transmission oil, no oil drizzles down onto the bearings.

A quick way to solve this problem is to stop every 30 miles and run the engine for 30 seconds or a minute. Leaving the car in neutral is fine. This might be a hassle, but 5 minutes every hour is likely much less time than it would take to disconnect the driveshaft.

[IRPancake]

You only need to disconnect the driveshaft if you are towing more than a limited number of miles -- 30 or 50 miles. Check your owners manual to find the recommended limit.

The problem isn't a pump -- the manual transmission doesn't have a pump. The problem is that with the car in neutral and the engine off, none of the gears inside the transmission spin. Only the output shaft spins. Without the gear teeth dipping into the transmission oil, no oil drizzles down onto the bearings.

A quick way to solve this problem is to stop every 30 miles and run the engine for 30 seconds or a minute. Leaving the car in neutral is fine. This might be a hassle, but 5 minutes every hour is likely much less time than it would take to disconnect the driveshaft.

driveshaft on the diff end is only 4 bolts that are easy to get to. Also would having the engine on in neutral spin the gears?

[JoshS]

No, he's talking about towing his car behind his RV as a regular occurance, I think. To do that you want a way to disconnect the driveshaft easily and quickly every time you hook up.

http://www.remcotowing.com/node/7

Unfortunately, I don't think anyone makes one of these things specifically for BMWs, so you'd have to adapt one built for another application, which could get pretty expensive.

Also would having the engine on in neutral spin the gears?

Yes, the transmission is lubed by the input shaft, not by the output shaft. Are you suggesting that he should leave his engine running while he tows his car?

[djb2]

Running the engine with the transmission in neutral does spin all of the gears.

Manual transmissions are "constant mesh". All of the gears are permanently engaged, but spin around the output shaft on bearings. When you select a gear, an assembly comes in from the side and locks only that gear to the output shaft. The avoids chipping the edge of the gear teeth during engagement, or having only the edges of the gears engaged.

[Randy Forbes]

driveshaft on the diff end is only 4 bolts that are easy to get to. Also would having the engine on in neutral spin the gears?

You can undo the four (4) nuts at the driveshaft/differential flange, but there is insufficient movement to slide the driveshaft forward enough to get the studs clear of the flange.

There is the possibility of loosening the gland-nut at the center (driveshaft support) bearing, and perhaps the spline can be compressed enough for the studs to clear the differential flange.

The short answer is no to the dolly, and yes to the small tilt-bed trailer.

Other comments about oiling, method of oiling and gear selection (constant mesh) are all correct.

[IRPancake]

No, he's talking about towing his car behind his RV as a regular occurance, I think. To do that you want a way to disconnect the driveshaft easily and quickly every time you hook up.

http://www.remcotowing.com/node/7

Unfortunately, I don't think anyone makes one of these things specifically for BMWs, so you'd have to adapt one built for another application, which could get pretty expensive.


Yes, the transmission is lubed by the input shaft, not by the output shaft. Are you suggesting that he should leave his engine running while he tows his car?

no no not at all, obviously by my other post I'm not the most knowledgable but I would never suggest that. I just wasn't sure if it spun the gears or not.